Electric control device



June 29, 1937.

w. F. SKEATS 2,085,549

ELECTRIC CONTROL DEVICE Filed Oct. 17, 1935 OIL LEVEL.

Inventor": WHFr-eci F2 Skeats AMZM fI mttor hey.

Il atented June 29, 193? UNITED STATES ELECTRIC CONTROL DEVICE Wilfred F. Skeats, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application October 17, 1935, Serial No. 45,417

8 Claims.

My invention relates to electric control devices, more particularly to an electromagnetic device for controlling the relative position of a portion of the conducting path, either solid or gaseous, of an electric circuit, with respect to a magnetic circuit by and-in accordance with the magnitude of. the current traversing said circuit.

In accordance with my invention in a preferred embodiment thereof, an electric circuit interrupter of the oil or fluid-blast type is provided with electromagnetic means including a magnetic path which is linked by the are upon opening of the circuit, arranged so that within a predetermined range of current the arc is moved in one direction and lengthened, and beyond the aforesaid range of current is moved in the op- :posite direction towards or maintained in a position of normal or shortest possible length.

With such control of the .arc, the arc pressure, which in interrupters of the aforesaid type is utilized to cause an arc-extinguishing fluid blast, is regulated so that the pressure is increased at :low current by lengthening of the arc, and at high current when the pressure is entirely adequate or in fact may even be excessive the arc is automatically shortened to its normal length.

Further, in accordance with broader aspects of my invention, the electromagnetic arrangement may control the relative position of a solid electric conductor forming part of an electric circuit for indicating, for example, when the magnitude of. the current in said circuit is within predetermined limits.

My invention will be more fully set forth in the following description referring to the accom-= :panying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. l. is an eleva tional view, partly in section, of a portion of an electric circuit breaker embodying my invention; Fig. 2 is a sectional plan view taken along the line 2-2 of Fig. 1; Fig. 3 is a view, partly in section, illustrating the application or my invention to a relay or contacts, and Fig. 4 is a plan view of the electromagnetic device shown in Fig; 3.

Fig. 1 of my invention is illustrated as applied to an oil circuit breaker of the oil-blast type comprising an oil-containing casing i, the oil level being indicated, and relatively movable con tacts 2, 3 and i immersed in the oil for opening the circuit. The contact structure 2, which (Cl. ZOO-15d) is fixed and electrically connected to the casing i forming one terminal of the circuit breaker, is of the socket type as indicated at 2' for receiving the movable rod contact t. The contact structure 3 comprises a pair of pivoted conducting gate members 3' which are normally biased by springs, as illustrated, into engagement so as a to be interposed in the path between the stationary contact 2 and the movable rod t. When the rod 4 is lowered to close the circuit at the contact 2, the gates 3' are pushed apart and make sliding electrical contact with the sides of the rod 4i. When the rod d is raised to open the circuit the conducting gates 3', which form in eiiect intermediate contact structure, divide the are into two sections, that is, a primary or pressure generating are between the contacts 2 and 3 and a main are subject to the oil blast between the contacts 3 and i.

For the purpose of directing the oil blast caused by the pressure generating arc insulating baffle structure 5 is mounted in the casing so as to form a passage 6 which communicates with the pressure generating arc and traverses the main arc to exhaust above the insulating bafiie. The baffle b, which also supports the intermediate contact structure 3, is provided with a vertical bore i for guiding the rod contact d.

An oil-blast circuit breaker as above described forms no part of the present invention and is described and claimed in U. S. Patent No. 19%,- 224=,*granted February 13, 1934, to William E. Paul for Circuit interrupting apparatus.

In an oil-blast circuit interrupter of the above type the operation within a comparatively wide range of current may not be uniform, particularly at high voltages, due to the fact that at low current insumcient pressure may be generated by the are for creating an effective oil blast. At highcurrent the blast is most efiective and the circuit is quickly and positively interrupted within the higher range of current.

In accordance with my invention, the primary or pressure generating are between the contacts 2 and t is automatically regulated in accordance with the arc current so that the arc is looped and lengthened at low current for increasing the arc pressure and is maintained in the normal or position of. shortest possible length at high current. To this end an electromagnetic device 8 is mounted in the casing i between the contacts 2 and 3 so that the pressure generating arc is drawn adjacent or through said device. in the present arrangement the electromagnetic device 8 comprises an insulating block or disk ii of a 2 sonata-o suitable material in which is molded a soft iron core it, as best illustrated by Fig. 2. Ellie core in is preferably laminated as shown at ii and is completely enclosed and insulated by the insu- 5 lating material at 9. The disk 9 is provided with a central aperture l2 through which the rod contact l operates, thereby linking the electric and magnetic circuits. A lateral slot i2 extends from aperture 12 towards the periphery of the disk;

The iron core fill is positioned so that it closely surrounds the aperture i2 and slot i2 as illustrated by Fig. 2, the portion of the core surrounding the slot it being of comparatively 15 small cross section, as at M, so that that part of the magnetic circuit can be readily saturated, and the opposite part of the magnetic circuit of comparatively large cross section, at H, is pro vided with a magnetic gap.

Therefore, at low current the magnetic field established by the are which is drawn centrally of the core It] causes, in accordance with well known principles, looping of the are into the slot 12' as indicated by Fig. 1. 'Ihat is, at low currents the magnetic path I3 is not saturated and is traversed by the main flux, comparatively little flux flowing through the path at I by reason of the gap. Since the magnetic field established by the arc tends to seek a path of minimum reluctance, the arc is pulled towards or into the portion Hi. If desired, arcing horns or the like may be connected respectively to contacts 2 and 3 for facilitating movement of the arc into the slot l2. Accordingly, due to lengthening of the pressure generating are within the slot I2, the arc pressure is correspondingly increased and the oil blast through the passage 6 and across the main arc is more effective.

However, when the arc current reaches comparatively high values, the portion l3 of the magnetic circuit becomes saturated with the result that the flux which passes across the air gap between the non-saturable portions ll of the magnetic circuit continues to increase substantially in proportion to the current and so eventually predominates. As the flux in this part 01' the circuit increases and predominates, the arc is moved by the magnetic forces in the opposite direction and at predetermined high currents the arc tends to extend directly between the contacts 2 and 3 as normally drawn so as to have the shortest possible length. Thus the position and length of the are are automatically controlled in accordance with the magnitude of the current in the circuit to be interrupted without the use of auxiliary movable contact structure or movable elements.

In Fig. 3 my invention is illustrated, by way of example, as applied to a relay for indicating maximum and minimum current conditions in 'a. circuit. The laminated iron core In in the present instance is provided with a movable coil I! which is traversed by current in the circuit IS. The coil I5 is carried by a frame l5 suitably guided for reciprocal rectillnear movement about the portion l3, such as by an insulated rod II which is slidably mounted in the core ll as illustrated by Figs. 3 and 4 and is centered by light springs ii". The portion H of the magnetic circuit is provided with an air gap W as in the previous instance. The operation of the device is believed to be apparent from the above description. At minimum or low current the coil I5 is moved towards the right or saturable side and the rod H which carries a bridging contact it closes an indicating circuit lighting the signal lamp G. When high or maximum current is reached, the coil 35 is moved towards the left or comparatively non-saturable side so as to close through the contact it the circuit for en-- ergizing the signal lamp R, the principle of operation being identical with that previously described in connection with Figs. 1 and 2. Within a predetermined range there will be no visual indication. 10

It should he understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the 15 spirit of. my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. An electric control device comprising means forming a magnetic circuit having a saturable m portion and a comparatively non-saturable portion located substantially opposite said saturable portion and an electric circuit, said circuits be ing linked so that within a predetermined range oi current in said electric circuit there is rela- 2' tive bodily movement in the direction of one of said portions between the immediately linked portions of said circuits and beyond the aforesaid range of current said circuits tend to assume a relative position in the opposite direction. 30

2. An electric control device comprising means forming a magnetic circuit having a saturable portion and a comparatively non-saturable portion, said magnetic circuit being linked with an electric circuit arranged between said portions 5 so that a portion of said electric circuit immediately-linked with said magnetic circuit is moved in the direction of one or said portions when current insufficient to cause saturation 01 said saturable portion traverses said electric circuit, 40 and in the opposite direction when said current exceeds a value causing saturation of said saturable portion.

3. An electric control device comprising means forming magnetic circuit having a. saturable 45 portion and a comparatively non-saturable portion, said saturable portion defining an elongated slot, and an electric circuit linked with said magnetic circuit and arranged so that a. portion of said electric circuit is moved transversely of said 50 slot in one direction when current insuflicient to cause saturation of said saturable portion traverses said electric circuit, said portion being uppositcly positioned when said current exceeds a value causing saturation of said saturable por- 55 tion.

4. An electric control device comprising means forming a magnetic circuit having a saturable portion and a comparatively non-saturable portion, and an electric circuit including an are 60 linked with said magnetic circuit, said are being positioned adjacent said non-saturable portion so that there is movement of said are toward said saturable portion when current insumcient to cause saturation of said saturable portion trav- 65 erses said electric circuit, and in the opposite direction when said current exceeds a value causing saturation of said saturable portion.

5. An electric control device comprising means forming a magnetic circuit having a saturable [0 portion and a. comparatively non-saturable portion including an air gap. said saturcble portion ,deflning an elongated slot, on electric conductor forming part of an electric circuit which is linked with said magnetic circuit movable within said 1' slot in one direction when current insumcient to cause saturation or said saturable portion traverses said electric circuit, and in the opposite direction when said circuit exceeds a value causing saturation of said saturable portion, and means operatively connected to said movable conductor for indicating predetermined maximum and minimum currents in said circuit.

6. An electric circuit interrupter oi the oil blasttype having means forming a pressure generating arc, and electromagnetic means for moving transversely and lengthening said pressure generating are only in accordance with comparatively low current traversing said interrupter.

7. Anelectric circuit interrupter of the oil-blast type having means forming a pressure generating are, means forming a magnetic circuit having a saturable portion and a comparatively nonsaturable portion and linking the electric circuit including said are, said magnetic circuit arranged so that said pressure generating arc is lengthened when the arc current is insuflicient to cause satture arranged'to form a pressure generating arc and a, mainarc, an iron core forming a magnetic circuit which links said pressure generating are, said core having a saturable portion at one end and a. comparatively non-saturable portion including an air gap at the opposite end and arranged so that when the arc current is insufficient to cause saturation of said saturable portion the arc is lengthened and moved towards said saturable portion for increasing the blast effect at said main arc and is positioned at normal length near said non-saturable portion when the arc current exceeds a value causing saturation of said saturable portion. I

WILFRED F. SKEATS. 

